Citi estimates that, so far, the price hikes may have added $42 million in earnings for Woolworths.

Cross subsidies?

The report suggests there could be several reasons why the supermarket giant may be lifting certain grocery prices.

Firstly, that Woolworths is using food and liquor sales to make up for poor performance at its hardware and discount stores.

The financial woes of Masters - Woolworths's answer to Bunnings - are expected to get worse, extending 2013's $139 million loss into a $166 million deficit for the last financial year.

The retailer's struggling discount department store Big W, is expected to see earnings slide by 10 per cent.

Woolworths could also be using the extra cash to build a war chest of funds to be used later in promotions to more effectively fight Aldi and Coles, which together have been eating into Woolworths's market share.

Or Woolworths could simply be passing on higher supplier costs.

Woolworths and the suppliers listed have been contacted for comment.

In response, the supermarket giant says the analysis is superficial and, overall, grocery prices have been falling for more than four years.

"The sample of just 10 unrepresentative items taken by the analyst cannot accurately represent prices for an average shopper across the thousands of everyday goods," a Woolworths spokesperson said in a statement.

"Grocery prices continue to fall with 18 consecutive quarters of price deflation. Shoppers have saved an average of $445 each year per household over the last 5 years."